Surging gas production has led the drilling industry to seek out new markets for its products. And energy companies, increasingly, are setting their sights on the transportation sector, trying to boost demand for natural gas buses, taxis, shuttles, delivery trucks and heavy-duty work vehicles of all sorts.

Fleet managers are taking notice, with waste haulers and transit agencies leading the way in converting to natural gas.

But a lack of fueling infrastructure remains a high hurdle to consumer adoption.